/*
 * @Author: funlee
 * @Email: i@funlee.cn
 * @Date: 2018-01-12 00:23:00
 * @Last Modified time: 2018-01-12 00:23:00
 * @Description: arcTo(cx, cy, x2, y2,radius)
 *               控制点：(cx,cy) 
 *               结束点：(x2,y2) 
 */

window.onload = function () {
  var canvas = document.querySelector('.canvas')
  var cxt = canvas.getContext('2d')

  cxt.moveTo(20, 20)
  cxt.lineTo(70, 20)
  // cxt.stroke()

  // cxt.beginPath()
  cxt.arcTo(120, 20, 120, 70, 50)
  cxt.lineTo(120, 120)
  cxt.stroke()
}